The present invention relates generally to sealing devices for electrical connectors and more particularly to sealing devices for electrical connectors where the electrical connector is implanted within the body.
With the increasing use of implantable electronics, there is an increasing need for a device for and method of securely connecting the ends of two or more electrical wires and sealing the connector from the corrosive effects of the body, especially the human body.
Cochlear implants frequently involve inserting an electrode into the cochlea. When connected to suitable electronics this electrode produces the electrical stimulation of the auditory nerve which may represent a sensation of hearing in some persons. Often the electrode positioned in the cochlea is coupled directly to associated electronics with a continuous wire. Sometimes it is necessary or desired to change the associated electronics. Typically this is due either to a failure in the electronics or the desire to update the electronics to a more advanced version. Usually it is undesireable to replace the electrode at the same time. After the electrode is inserted into the cochlea, tissue grows around the electrode, making the removal and successful reinsertion of another electrode very difficult. Therefore, it is preferable to be able to cut the wire to the present electrode and to be able to connect a new wire and new associated electronics to that wire.
An electrical connector implanted in the body must be very reliable since surgery would be required to repair the connection. Even though the loss of hearing is not in itself life threatening, unnecessary surgery should be avoided. The electrical connector itself should be solid and secure. The connector should be protected from the severe corrosive environment of the body and the electrical connection should be electrically insulated from the body. The connector and its sealing mechanism should not be toxic to its host.
In order to seal an implanted electrical connection, it is known to slip an insulative tube over the connection and to fill the internal space around the connection within the insulated tube with a suitable sealing material, such as silicone rubber. Reference is made to a first international course on multi-channel cochlear implant presented in Paris on September 1-24, 1978, in an article by Chouard, Pialoux and MacLeod.
A major problem, however, is to provide a mechanism to enable the sealing material, e.g. silicone rubber, to be forced into the insulative tube easily and reliably so that the surgeon can accomplish the connection and sealing quickly and with confidence. The sealing material must completely surround the connection, preferably filling all voids between the insulative tube and the connection.
If sealing material is forced into one end of the tube, there is no guarantee that the sealing material will reliably fill all air spaces before being forced out the opposite end of the tube. If air spaces remain, the "voids" could effect the reliability of the seal and the resultant reliability of the electrical connection.